Outside:The scarlet tanager, common but hard to find

Written by By Mike Slater

Adult male scarlet tanagers are brilliant red with black wings and tails. They are strikingly conspicuous birds yet seldom seen even though they are common inhabitants of Pennsylvania's woodlands. This is because they like to hang out in the tree tops. Females are even harder to spot because their plumage is greenish overall with dark-gray or blackish wings and tail feathers.

If you become familiar with their songs and calls you will realize they are pretty common in Pennsylvania's forests. Their song sounds like a "robin with a hoarse throat," and their call consists of a falling two-note phrase "Peet-suh" or to some people "Pizza."

Their gray bill is a little thinner and longer than a cardinal's but shorter and thicker than a robin's bill. A scarlet tanager's bill is ideally suited to its prey, caterpillars and other insects that live in the leaves and branches of forest trees. Arthur C. Bent in his series of books on the "Life Histories of North American Birds" quotes the early 20th century ornithologist Edwin H. Forbush's succinct description of their diet: "In its food preferences the tanager is the appointed guardian of the oaks. It is drawn to these trees as if by magnets, but the chief attraction seems to be the vast number of insects that feed upon them. It is safe to say that of all the many hundreds of insects that feed upon the oaks few escape paying tribute to the scarlet tanager at some period of their existence." And he further describes the tanager's hunting strategy: "It is not particularly active, but like the vireos, it is remarkably observant, and slowly moves among the branches, continually finding and persistently destroying those concealed insects which so well escape all but the sharpest eyes."

So like so many of our native birds, tanagers are dependent on the caterpillars and other insects that feed on oak trees.

A scarlet tanager hitches a ride on a cruise ship near the Panama Canal.

Dr. Douglas Tallamy emphasizes this notion in his books and presentations: "If you want to do one thing to help birds, you should plant an oak tree."

Tanagers also eat gypsy moth caterpillars, at least when they are small. Forbush reported observing two tanagers eating small gypsy moths at the rate of 35 per minute. If they did this for an hour a day for a week that would be a total of 14,700 caterpillars for just two birds.

Because they are mostly insectivores, they have to go south to warm or hot climates during our cold winter months.

They leave here in September and head south, passing through Mexico and then Central America and finally spreading out through the forests of South America.

In February and March they begin to head north again, arriving back in Pennsylvania in May just as the oaks are flowering and beginning to leaf out.

I have only a few poor photos of tanagers from here in the U.S., but I was lucky to photograph the male pictured here as it was hitchhiking on our cruise ship.

We were on a cruise through the Panama Canal onboard the Celebrity Infinity, and the morning after we passed through the canal into the Pacific Ocean. We were just about to turn northward on April 8 when I heard from another passenger about a red bird sitting on the upper fore-deck of the ship. It had apparently landed on the ship during the night after we had exited the canal.

We went to look and saw it immediately. It seemed healthy but shy. Fortunately we were headed in the right direction as the ship turned north up the coast toward Costa Rica.

The bird was sheltered from the wind and getting a free ride. I looked for it the following morning as we slowed to enter the Costa Rican port of Puntarenas and it was gone.

I presume had taken off for the jungle as we approached land. I hope it made it back OK to its territory in the forests of the Northeastern USA and/or Canada in the three or so weeks it had left in the month of April.

The perils of migration are apparently worth the risk to birds such as this, as they are a pretty successful species despite the hazards that man and nature keep putting in their way.

I hope that they thrive for the millennia to come as our hazards and impacts on the environment continue to expand and we can help them by planting oak trees for caterpillars for them to eat and feed their babies.

Mike Slater is president of the Baird Ornithological Club and a member of the Mengel Natural History Society of Berks County and the Muhlenberg Botanic Society of Lancaster. He lives in Brecknock Township. Reach him at paplantings@gmail.com.